Bottomness

Template:Short description Template:Flavour quantum numbers In physics, bottomness (symbol B′; using a prime as plain B is used already for baryon number) or beauty is a flavour quantum number reflecting the difference between the number of bottom antiquarks (n_{Template:SubatomicParticle}) and the number of bottom quarks (n_{Template:SubatomicParticle}) that are present in a particle:

$B^{\prime }=-(n_b-n_{\overline{b}})$

Bottom quarks have (by convention) a bottomness of −1 while bottom antiquarks have a bottomness of +1. The convention is that the flavour quantum number sign for the quark is the same as the sign of the electric charge (symbol Q) of that quark (in this case, Q = −Template:Frac).

As with other flavour-related quantum numbers, bottomness is preserved under strong and electromagnetic interactions, but not under weak interactions. For first-order weak reactions, it holds that $\mathrm{\Delta }{B}^{\prime }=\pm 1$.

This term is rarely used. Most physicists simply refer to "the number of bottom quarks" and "the number of bottom antiquarks".

References

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